The present invention relates to novel substituted 5-(pyrrol-2-oyl)-1,2-dihydro-3H-pyrrolo [1,2-a]pyrrole derivatives and their corresponding salts, esters, nitriles, amides and substituted amides. Unlike the known pyrrolo[1,2-a]pyrrole derivatives of U.S. Pat. No. 4,097,579, which are limited to 5-unsubstituted pyrryl derivatives, the new compounds of the present invention have 5-pyrryl groups substituted with various groups including alkyl, 5-S-alkyl, ##STR1## 5-SO.sub.2 -alkyl, 5-alkyl, 5-N-alkyl, 5-O-alkyl or 5-halo. It has been a well-known fact that such hetero-substituted pyrroles are difficult to prepare due to the sensitive nature of the pyrrole system. Furthermore, the compounds of this invention are found to possess higher analgesic/anti-inflammatory activities but exhibit much lower ulcerogenic irritation than the prior art compounds. For a chronic disease, for example, arthritis, it is crucial that the anti-inflammatory/analgesic agent be administered routinely and regularly at an effective dosage level without causing gastric irritation or ulcer. Accordingly, it is an object of the present invention
(1) to provide novel nonsteroidal anti-inflammatory and analgesic agents with high potency but lower ulcerogenic side effect; PA1 (2) to develop processes for the preparation of the novel 5-(substituted pyrrol-2-oyl)-1,2-dihydro-3H-pyrrolo[1,2-a]pyrrole derivatives; PA1 (3) to provide methods of application of the novel compounds in the treatment of inflammatory diseases, the relief of pain and fever or inhibition of platelet aggregation; and PA1 (4) to provide pharmaceutical compositions and formulations for the administration of these novel compounds.